Remove the OnError method from notification delegates.

content/common/desktop_notification_messages.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // IPC messages for desktop notification.
 // Multiply-included message file, hence no include guard.
 
 #include "content/public/common/show_desktop_notification_params.h"
 #include "ipc/ipc_message_macros.h"
 
 #define IPC_MESSAGE_START DesktopNotificationMsgStart
 
 IPC_STRUCT_TRAITS_BEGIN(content::ShowDesktopNotificationHostMsgParams)
   IPC_STRUCT_TRAITS_MEMBER(origin)
   IPC_STRUCT_TRAITS_MEMBER(icon)
   IPC_STRUCT_TRAITS_MEMBER(title)
   IPC_STRUCT_TRAITS_MEMBER(body)
   IPC_STRUCT_TRAITS_MEMBER(direction)
   IPC_STRUCT_TRAITS_MEMBER(replace_id)
 IPC_STRUCT_TRAITS_END()
 
 // Messages sent from the browser to the renderer.
 
 // Used to inform the renderer that the browser has displayed its
 // requested notification.
 IPC_MESSAGE_ROUTED1(DesktopNotificationMsg_PostDisplay,
                     int /* notification_id */)
 
-// Used to inform the renderer that the browser has encountered an error
-// trying to display a notification.
-IPC_MESSAGE_ROUTED1(DesktopNotificationMsg_PostError,
-                    int /* notification_id */)
-
 // Informs the renderer that the one if its notifications has closed.
 IPC_MESSAGE_ROUTED2(DesktopNotificationMsg_PostClose,
                     int /* notification_id */,
                     bool /* by_user */)
 
 // Informs the renderer that one of its notifications was clicked on.
 IPC_MESSAGE_ROUTED1(DesktopNotificationMsg_PostClick,
                     int /* notification_id */)
 
 // Messages sent from the renderer to the browser.
 
 IPC_MESSAGE_ROUTED2(DesktopNotificationHostMsg_Show,
                     int /* notification_id */,
                     content::ShowDesktopNotificationHostMsgParams /* params */)
 
 IPC_MESSAGE_ROUTED1(DesktopNotificationHostMsg_Cancel,
                     int /* notification_id */)
 
 IPC_SYNC_MESSAGE_ROUTED1_1(DesktopNotificationHostMsg_CheckPermission,
                            GURL /* origin */,
                            int /* permission_result */)